The Nuclear Regulatory Commission says it will make a decision in April or May regarding when Southern California Edison can restart one of two reactors at the plant.
Edison predicts running the Unit 2 reactor at reduced power will stop tube damage. Environmentalists disagree and believe the plant cannot run safely.
"The NRC will not allow the plant to restart until we are satisfied that the licensee can operate the plant without undue risk to public health and safety," the agency said on its website.San Onofre shut down over a year ago after workers discovered excessive wear in reactor tubes that carry radioactive water.
Federal regulators said they will hold a public meeting in Southern California before a decision is made.
